Usually the purpose for the playback of videos in a surveillance system is to search for a certain person, object or event. If a time point where a target object appears or occurs is unknown, users usually prefer to fast forward the playback videos until finding the target object, and then review them in slow motion. On a common playback user interface, users have to suspend the playback videos immediately when finding the target object, and then rewind the video or pull a slider backward till a certain time point of the time line that the target object appears.
During the playback, each action to manually operate the surveillance system, such as pushing buttons, keyboard operation or mouse operation, requires a response time for the human brain to control the hands to do the action in response to visional stimulation. Therefore, such a human response time may not fit in the playback of videos on a machine, especially when users operate the interface wrongly or with confusion. For example, when a user reactively suspends the playback, the playback progress herein may exceed a desired play time point, resulting in that the user must rewind the video to search for the target object again. If forgetting to slow down the playback, the user herein has to rewind the video to search for the target object again. However, no one wants to repeatedly rewind and search again and again until a clip of the video that the target object can be observed clearly is found.